Comparison of Synovial Fluid Composition in Distended and Normal Digital Flexor Tendon Sheath (DFTS) of Horses: A Pilot Study

This study is designed to examine biochemical (serum amyloid A (SAA), haptoglobin (Hp) and D-dimer) and cytological (total nucleated cell count (TNCC), neutrophil, lymphocyte, and monocyte count) characteristics of serum and synovial fluid of the equine DFTS. Twenty-eight adult horses of different breeds were used in this study. Synovial fluid samples were aseptically collected in EDTA from 43 limbs in 20 horses with (study group) and 8 limbs in 8 horses without (control group) distention of DFTS. Lymphocyte, monocyte, neutrophil, and TNCC in the synovial fluid were statistically higher in the distended sheath that shows an inflammatory nature of the distention, however, concentrations of D-dimer was lower in serum (0.1, 0.10 - 3.80) & (0.2, 0.10 - 0.20) than synovial fluid (19.2, 17.78 - 20.00) & (20, 19.90 - 20.00)) in both groups. The serum SAA concentrations of the control group (1.7, 0.10- 2.16) were significantly higher than the study group (1, 0.86 - 1.05) and the concentration of SAA in serum was higher than synovial fluid (0.89, 0.86 - 0.98) in the control group. Results of this current study show that a cytological evaluation of the synovial fluid is more valuable than biochemical findings in the diagnosis of the inflammatory nature of this condition.